I have no idea what they do in qemu-kvm. There is no ia64 support in
upstream QEMU.

*shrug*. I just figured it might be worth considering, since the plan
was to get qemu as capable as qemu-kvm, no?

I do, but there's a lot of work to get ia64 there primarily due to the
fact that there is no target support for ia64 in qemu. The upstream
implementation is going to end up significantly different than the
qemu-kvm implementation.